1. Field
The invention is concerned with both the treatment and the transportation by pipeline of hydrocarbon gases containing potential atmospheric pollutants, so that a fuel gas, such as "sour" gas from wellheads and fuel gas derived from coal gasification, is delivered at a desired destination as a substantially clean-burning fuel, and so that an exhaust gas, as from gas turbines or coal burners, can be safely discharged into the atmosphere without danger of air pollution.
2. State of the Art
Hydrocarbon gases are normally transported by pipeline from the sources of same to points of distribution and use. It is customary to treat such gases, if treatment is deemed desirable, prior to introducing them into a pipeline for transport or at the destination prior to use.
Although natural gas has long been transported great distances by pipeline for ultimate use as a fuel or as a raw material for industrial use, the energy potential of coal has customarily been exploited by burning the coal to power electrical generators at or as near as possible to the source of the coal and by transmitting the electrical power so generated to densely populated areas for use. This avoids air pollution in such densely populated areas and is cheaper than transporting the coal itself.
Gasification of coal in or near cities and distribution of the resulting gases for use as a fuel has been practiced in the past and is still practiced in various places throughout the world, but whenever economically possible this has been replaced by supplying natural gas by pipeline or by supplying electricity by high voltage power lines as previously indicated. Coal has not been favored as a fuel or other energy source, largely because of atmospheric pollution when burned.
Often natural gas wells produce so-called "sour" gas, which requires treatment for the elimination of sulfur and other compounds that pollute the atmosphere when burned. Again, fuel-burning equipment, such as gas turbines, coal burners, etc., usually emit exhaust gases that heavily pollute the atmosphere unless prohibitively expensive means are utilized to remove the pollutants before the gas is released. Thus, the State of California, for example, prohibits the use of gas turbines or coal burners for the generation of electricity or to power industrial activity.
3. Objectives
In the making of the present invention, primary objectives were to utilize any sensible heat energy of an unpurified fuel gas to maximum extent while transporting it to a point of ultimate use as a fuel; to substantially eliminate possible environmental contaminants of the fuel gas or of other gases during transportation thereof by pipeline, without pollution of the environment; to take advantage of the very substantial economies of pipeline transport of a fuel gas, as opposed to using it at its source for the generation of electricity and then transmitting the electricity, while introducing further economies by utilizing the pipeline as a heat exchanger in the treatment of the gas during transport to both recover sensible heat energy which it may initially contain and to remove potential atmospheric pollutants therefrom so that a substantially clean-burning fuel gas is delivered at the destination. Further objectives were to deliver high purity hydrogen for use as a fuel gas or otherwise, at the exit end of a cross-country gas pipeline into which gas from a coal-gasification plant is fed, to make practical the use of gas turbines in areas where they are ordinarily prohibited, and to provide economically for the elimination of pollutants from any effluent gas and from "sour" natural gas during delivery from the wellhead.